“Ten prints” is a generic term used in the art to mean a set of fingerprints which may be taken either directly from a person's fingers or palms, or may be scanned from a print card. Prints taken directly are obtained by placing the fingers (and/or palms) on a scanner or by inking the fingers, etc. onto a paper card. Each print contains minutia features which have respective X-Y coordinate positions and angles of orientation as conventionally known in the art.
For many civil and criminal applications, such as identification verification, immigration control, etc., it is necessary to match the ten prints obtained from a person to ten print records stored in a database. In conventional automatic fingerprint identification systems (AFIS), the fingerprint features are captured from a person's ten prints to form what is termed a “search record”. In a similar manner, the fingerprint features extracted from ten print cards of known identities have been stored in a database as “file records.” To determine a match, a search record and the file records are compared in a fingerprint matcher microprocessor and matcher scores are determined as a measurement of how similar the compared minutiae are.
In the prior art, a minutiae matched score is determined for each of the ten fingers (or palm print) relating to the number of individual minutiae of that finger of the search record that compares to the minutiae of the same finger that is in the file record. The higher the score, the more similar the search and file prints are determined to be. The scores are then added for the compared fingers (that may be less than 10) of the search to the file records, and then dividing the score totals by the number of fingers compared, to thus obtain an average matched score. A sorted list may be compiled from candidate file records, and a subset of candidates are selected based on an average score threshold. This subset is then sent to an examiner for review to determine the correctness of the matched prints. Since each potential matched record must be visually verified, the selection of an accurate candidate list is quite important in the process. The amount of time and energy to review a large list of candidate records is a drain on resources that are becoming more stretched as the demand for fast and accurate identification services are required. If the list is too small, the mated candidate may not be in the list since the method of averaging matched scores does not take into account even if a pair of fingerprints is matched. Even if two of the compared finger pairs exhibit high match scores, lower match scores for the rest of the fingers may override the observed results. Thus lower match scores that may result because of operator differences in pressure or technique in obtaining the prints, smudging of the prints or background noise may cancel out the higher match scores for some of the fingers of the sets that are legitimate and valuable in determining the identification of an individual. Solutions to these problems, to date, have included increasing the number of manual examiners required to provide the identification results in a timely fashion or to forego accuracy in lieu of speed.
Thus, an enhanced system and method of identification using, for example, a ten print to ten print search that provides reliable decision logic and accuracy in the initial computer search of prints remains a goal in this area. It would be desirable to have an adaptive multi-level matching and decision logic system and a method that provides decision for the individual pairs of matched prints and records, that better utilizes the resulting scores in a progressive rather than an averaged score to more accurately obtain the desired identification and fast response time.
Those skilled in the art will appreciate that elements in the Figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the Figures may be exaggerated relative to other elements to help improve understanding of various embodiments of the present invention.